The leaf extracts of bamboo (Shibataea chinensis Nakai) and its fractions (Ethyl acetate, n-butanol and water) obtained after extraction with petroleum ether, were assayed on seed germination and seedling growth of lettuce (Lactuca sativa L. var. ramosa Hort.) and cucumber (Cucumis sativus L.). The leaf extract showed the lowest phytotoxic activity, while, the n-butanol fraction was most bioactive on germination and seedling growth of both target plants. A bioassay-guided fractionation of the n-butanol fraction led to the isolation of five phytotoxic compounds. The chemical structures of these substances were elucidated by nuclear magnetic resonance as apigenin (I), quercetin (II), daucosterol (III), 3, 3’, 4’, 5-tetrahydroxy-7-methoxyflavone (IV) and p-methoxybenzoic acid (V). The Quercetin, apigenin and daucosterol were more phytotoxic to germination (IC50=7.26-7.95 ppm), root (IC50= 2.97-6.33 ppm) and shoot elongation (IC50=4.89-7.74 ppm) of lettuce than glyphosate (IC50 values >20 ppm). In cucumber, the p-methoxybenzoic acid showed similar phytotoxic activity (IC50 = 20 ppm, 6.93 ppm, 10.45 ppm, respectively) to glyphosate (IC50=20 ppm, 7.71 ppm, 10.84 ppm, respectively). Our research suggested that the leaves of S. chinensis have potent allelochemicals and their potential as herbicide should be further investigated.
Kuang† et al. (Sun,) studied this question.